Water, wind, and calcite erosion in per-volcanic sandstone formation.
Slightly acidic rainwater seeps into the sandstone during winter rains and dissolves some of the calcite. Warm and dry days cause …
This well-maintained trail offers fantastic views of the San Francisco Bay, Mount Diablo, the Livermore Valley and the Sacramento River Delta. In the spring, many wildflowers bloom on the green …
The Wind Caves are part of an area called Rock City in the Mount Diablo State Park. The Wind Caves are unique sandstone caves and tunnels that were formed by …
The origin of this unusual little underground dwelling is unknown. You can see a round stovepipe hole, a square skylight, and a shelf opening from the interior.
This unusual little underground dwelling's origin is unknown. From the interior, you can see a round stovepipe hole, a square skylight and a shelf opening.